1. Field of the Invention
The present invention relates to a device for supplying a liquid developer from a toner container to a tank and from the tank to a developing unit which is operable with the liquid developer.
2. Discussion of the Background
A liquid developer supply device of the type described has a tank storing a liquid developer, a toner container mounted on the tank upside down, and a dispersant bottle also mounted on the tank in an upside down manner. A pump is disposed in the tank for compressing the liquid developer. The liquid developer, i.e., a mixture of toner ejected from the toner container and dispersant fed from the dispersant bottle is fed by the pump to a developing unit or a cleaning unit through a supply conduit and is returned to the tank by a return conduit. The liquid level in the tank is sensed by a float switch. A nozzle having an inlet port and a nozzle hole is affixed to the mouth of the toner container. When the toner container is mounted on the tank, the inlet port of the nozzle is opened to feed the toner from the container into the tank via the nozzle hole. The dispersant fed from the dispersant bottle is mixed with the toner to form the liquid developer. The toner container mounted on the tank is usually positioned such that the nozzle hole of the nozzle is dipped in the liquid in the tank. Should the liquid level become lower than the nozzle hole of the nozzle, the nozzle hole would be exposed to the atmosphere and stopped by the toner which would dry and deposit on the nozzle then. However, the problem is that the liquid level in the tank is not always constant since the developer consumption and the amount of developer fed to and returned from the developing unit are not constant. It, therefore, often occurs that the nozzle hole of the nozzle is exposed to the atmosphere due to the fall of the liquid level. Then, the toner dries and sticks to the nozzle to stop the nozzle hole.
The above problem will be eliminated if the nozzle hole of the nozzle remains in the liquid even when the liquid level in the tank is changed. For this purpose, the toner container may be provided with an extremely long nozzle or may be bodily located in a lower position, as proposed in the past. However, a toner container having a long nozzle is not easy to handle and apt to break the nozzle when dropped. Lowering the position of a toner container is not desirable since the container would be dipped in and wetted by the liquid over substantial part thereof and, therefore, not easy to handle.